The present invention relates to printing apparatus, and more particularly, the present invention relates to multi-element dot printers or the like for recording information, for example, on metallized paper strips.
Plotters, writers, printers, of the type to which the invention pertains in the general sense may include, for example, a measuring instrument which receives the signal or value to be recorded, and the instrument has a pointer constructed as an electrode. The electrode is in contact with paper having a metallized backing, and upon application of a voltage between the electrode-pointer and the metallization, the pointer will burn a dot or a trace into the paper. The paper advances in a particular direction and the pointer undergoes a deflective movement with a component generally perpendicular to the direction of movement of the paper; thus, a time-amplitude curve composed of dots is "burned" into the paper in that manner. Particular recording devices may include relays, the armature of which carries such a pointer serving as an electrode. Normally, the electrode is disengaged from the paper. If a particular event, disturbance, alarm condition or the like occurs, the relay responds and deflects the pointer by a few millimeters and a recording will be made. Error or interference recorders of that type may require a number of variants, particularly in view of the number of measuring points to be supervised in that manner. Another variable is, of course, the width of the recording strip, and the association of the various pointers with the different measuring points, alarm conditions, etc. Equipment of this type often requires, in addition, a somewhat flexible distribution between the various locations and test points on one hand, and the particular input channels of the recorder on the other hand. The variations here may well require different overall construction of a particular type recorder so that a particular multi-channel and/or multi-purpose recording device may have to be assembled in accordance with the particular intended use of employment. Moreover, a change from one type of equipment to another type of equipment is often not possible once a particular assembly has been completed.
Utilization of a fixed recording system is, of course, desirable, having a number of comb-like arranged electrodes. By way of example, 256 comb prongs and electrodes may be included here with a total recording width of about 120 millimeters. Rather expensive recorders and special relays may be avoided in such an instance, if this particular comb arrangement cooperates with equipment which selectively associates measuring values with particular electrodes. On the basis of such a principle, a generalized piece of equipment can be realized if it is possible to preprocess the various measuring values in such a manner so that, indeed, the various electrodes are always directly operated by the associating equipment. Such a generalized or universal equipment system may well be suited for obtaining different kinds of recordings and permissing employment under different conditions and for different purposes as far as plotting, recording, etc., in general is concerned.
The German printed patent application No. 1,798,058 discloses a recorder with at least two input channels receiving signals to be recorded. Each channel includes an analog to digital converter which converts the analog signal in the respective channel into a binary, i.e., multi-bit signal. This particular recorder includes, in addition, a multiplexer which feeds the binary data from the input channels to a decoding matrix. This particular associating device decodes the binary values and energizes selectively one of a plurality of electrodes. The electrodes are arranged across an electrographic strip. This way, the signals are plotted one after the other. The delay between two sequential recording pulses is only a fraction of a second so that all signals are practically simultaneously recorded in the form of a row of dots. The delay in-between the recording of any two dots is practically zero. However, it was found to be disadvantageous that each channel requires its own analog-to-digital converter. Since in this particular recorder each signal is recorded practically over the entire recording width of the strip, the number of signals that can be recorded concurrently is inherently limited unless the various recordings interfere, which, of course, is to be avoided.